The Merida Initiative, signed by President George W. Bush and Mexican leader Felipe Calderón in 2007, promises Black Hawk helicopters, night-vision goggles and drug-sniffing dogs, as well as a more robust crime-fighting partnership between the United States and Mexico. So far the United States has delivered 2 percent of the equipment and support promised, according to the report by the Government Accountability Office.

The perception of a slow flow of aid has rankled some in the Calderón government and fueled criticism here that the United States, which spends billions consuming illegal drugs, is fiddling while 50,000 Mexican soldiers and police officers are fighting in the streets to confront powerful criminal organizations that threaten Mexico's national security.

The Merida Initiative did not lay out a specific timeline for delivering the U.S. assistance, but the report made clear that the pace of spending was lagging.

"Few programs have been delivered and limited funding has been expended to date," GAO investigators said. They said State Department officials "could not tell us when they planned to deliver the majority of Merida goods and services."

But the new U.S. ambassador to Mexico, Carlos Pascual, countered that the GAO report creates a "misimpression." He said that the United States has actually spent $222 million but that "due to the idiosyncrasies of federal reporting and contracting," many up-and-running programs have not yet shown up on the books as money "spent."

For example, Pascual said, a new federal police academy that has graduated more than 3,000 cadets taught by U.S. instructors is not reflected in the GAO accounting because contractors have not submitted invoices yet.

Similarly, the ambassador said, next week the U.S. government will deliver to Mexico five new Bell helicopters worth $66 million.

Some members of Congress, however, have been frustrated by what they see as a sluggish pace. "As President Calderón confronts his country's brutal drug cartels head on, we must cut through our own government's red tape to get Merida Initiative assistance flowing to Mexico more quickly," Rep. Eliot L. Engel (D-N.Y.), chairman of the House Foreign Affairs subcommittee on the Western Hemisphere, said upon releasing the GAO report.

This week, Calderón warned that the cartels are increasingly using drug money to buy off local politicians and attempting to manipulate elections.

Jeffrey Davidow, a former U.S. ambassador to Mexico who is now president of the Institute of the Americas in San Diego, said, "I don't think the slowness in the outlay is any kind of indication of a policy failure." Instead, he said, "it is better to take the time and get it right."

The GAO report notes that the Merida Initiative also includes $175 million in appropriated funds for nations in Central America and the Caribbean. It found that $2 million has been spent there.